The projected studies employ the recently isolated human insulin receptor to study the mechanism of transmembrane signalling and the means by which the pleiotypic insulin response can be generated from insulin binding to the receptor. By judicious alteration of the receptor cDNA, including domain swaps with homologous and heterologous receptors, formation of truncated receptors and mutagenesis and subsequent expression in heterologous cells, we propose to determine the structural requirements for the insulin specific responses including binding, internalization and the various insulin specific functions. We will search for the intracellular effectors of the response in cells overproducing the receptor. The structural basis of transmembrane signalling will be analyzed by employing panels of monoclonal antibodies to various regions of the molecule as probes and physical methodologies if possible. We will test the role of cellular localization and mutagenesis of the tyrosine kinase domain as causes for cellular transformation. The IR cDNA sequence will be employed as a probe to isolate and characterize the unique regions of interest in the IR gene and study the control of its expression in a variety of cell types. Recombinant constructs of IR regulatory regions linked to reporter functions will be used to test the regions of the gene controlling IR gene expression. Attempts will be made to analyze possible defects in IR structure or regulation in human populations. Finally, using methods similar to those required for isolation of the IR gene we propose to isolate and characterize the IGF-I receptor and carry out comparative studies with the insulin receptor.